As it is known, railway accidents occur more frequently nowadays, and some of these have minor consequences, but others have catastrophic consequences.
The current conditions which contribute to the increase in accidents are multiple. It has been found that there is a greater number of people travelling and therefore a greater number of trains moving. The means of transport are becoming increasingly sophisticated but are more prone to problems, and in fact, there is an increasing amount of electrical equipment present (air conditioning, automatic door opening and closing, static converters, electrical conductors for heating systems, etc.) which make the train more comfortable, faster and more modern but also more delicate and liable to problems such as come short circuits or overheating in certain parts which could facilitate the starting of fires.
The higher travelling speeds of the trains also facilitates the overheating of metal parts which could start or facilitate the spread of a fire.
In addition to the aforesaid points, for example, inside the carriages there are fabrics which, although they are fireproof, in the event of a fire, release toxic fumes that are highly dangerous for the passengers.
At the moment, for the very reason of the high potential for problems, there is a particular need to increase the safety levels in the trains both to protect the passengers and the railway staff and also the trains and the environment.
Particular studies performed to bring about higher safety standards have considered a situation in which the danger is great and, in particular conditions, the consequences would be extremely serious.
The aforesaid situation refers to a fire, even a relatively small fire, on a train travelling through a tunnel.
The situation analysed was that of a train with twelve to sixteen carriages, therefore potentially capable of transporting from seven hundred to nine hundred people, on which a fire starts at a certain point of the route. The panic and chaos it would cause are unimaginable and the obvious reaction of many people would be to stop the train by pulling the emergency brake in order to be able to get off and reach safety. If the emergency brake were pulled, for example, at the entrance to a tunnel three or four kilometres long or longer—and there are many of these tunnels—depending on the speed, the train would stop at least a kilometre into the tunnel. If the emergency brake used were that of the carriage in which the fire had broken out, no-one would be able to reach that point to reset the brake and there would be absolutely no possibility of the train moving with the further consequence that the panic and the chaos would become uncontrollable and there would be practically no possibility of reaching safety for nearly the totality of the persons because of the fire, the combustion fumes, the confined space within the tunnel and the impossibility of rescue workers intervening.
In clarification of the points made so far, a general explanation should be given of how the brakes on trains work. A main conduit starts at the locomotive of the train and is present in each carriage. When a train is composed, the different portions of the main conduit are connected together to make a single conduit through which air passes at a pre-set pressure which is used to keep the brakes in a non-operative condition. When the driver wishes to stop the train, he must simply decrease the air pressure in the main conduit and this decrease in pressure will activate a braking device which controls and activates a pneumatic system which engages the blocks or the disks on the wheels and stops the train. To deactivate the brakes, he must simply increase the pressure in the main conduit again. The emergency brake also works in a similar way and, in fact, the pulling of a handle located in each carriage causes air to be released from the main conduit and makes the braking device described earlier intervene, leading to the train braking and consequently stopping.
In more detail, nowadays, when the emergency brake handle is pulled downwards, a clamping element is released which, driven by a spring, pushes a piston upwards, the said movement opening a passageway for the air to flow through from the main conduit towards the external atmosphere. In this way, by lowering the pressure in the main conduit, one activates the train's brakes. To reset the brake, the intervention of the railway staff is indispensable, who must, in fact, reposition the handle that has been pulled, and in doing so, the clamping element is hooked up and the piston to close the passageway for the air is pulled down.
Clearly, it is only possible to work on the handle concerned and there is at least one in each carriage so if a fire broke out in the carriage where the handle has been pulled it is impossible for the brake to be reset and the train can no longer move. If the situation described occurred in a in tunnel, it would be even more difficult to intervene with all the consequences of the case.